The supply of therapeutic oxygen to patients in homes and other residential settings is an important and growing segment of the health care industry. Oxygen can be supplied to a patient by liquid or compressed oxygen with an appropriate vaporization or pressure regulation system and a gas delivery cannula. Alternatively, oxygen can be supplied by the generation of oxygen using a small onsite air separation device or medical oxygen concentrator located near the patient that delivers the generated oxygen via a cannula.
Respiratory oxygen usage rates typically range up to 3 LPM (liters per minute at 22° C. and 1 atma pressure) for ambulatory patients with relatively low oxygen requirements, up to 5 LPM for patients with more serious respiratory problems and possibly limited mobility, and in certain cases up to 10 LPM for those with the most serious respiratory problems and more limited mobility. A patient initially may require a higher oxygen supply rate during an illness and later may require less oxygen as recovery is achieved. Alternatively, a patient may require increasing oxygen rates as a chronic condition worsens. A conserver may be used to provide oxygen flow only when the patient inhales, thereby reducing the amount of oxygen required by eliminating the supply of oxygen that is wasted when the patient exhales.
Portable medical oxygen concentrators often are preferred over liquid or compressed oxygen supply systems in home and residential settings, and small air separation devices for these applications are being developed by numerous vendors in the home health care field. Patients typically are encouraged to be ambulatory whenever possible to increase the effectiveness of oxygen therapy and improve their overall health. The portability of a medical oxygen concentrator therefore is an important feature allowing the patient to move about easily and comfortably. In order to maximize portability and ease of use, the medical oxygen concentrator must be designed to have minimum weight and compact dimensions. Patient ambulation time can be maximized by the use of a conserver.
There is a need in the home health care field for an improved, lightweight, battery-powered portable oxygen concentrator for delivering oxygen product to ambulatory patients. These patients typically require a concentrator that can generate up to about 3 LPM of oxygen on a continuous basis and that includes a built-in conserver that maximizes ambulation time. This need is addressed by the embodiments of the invention described below and defined by the claims that follow.